This invention relates generally to a high pressure gas source, and, more particularly, to a hydrazine thermal bed gas generator which utilizes the heat capacity of heat retaining balls to sustain the heat required for the continued decomposition of hydrazine in order to produce gas under extremely high pressure.
Hydrazine gas generators are being extensively used for the generation of a heated gas discharge utilized primarily for the mode of power of vehicles either supported on land, water or in the air. The hydrazine gas generator operates on the principal of distributing liquid hydrazine into a decomposition chamber and the subsequent exothermic conversion of the hydrazine into gaseous products and heat, together with the discharge thereof through a nozzle to produce thrust. Many methods have been utilized to distribute the liquid, these include submerging liquid distribution nozzle outlets deep within the bed of a catalyst material, utilizing small diameter capillary tubes as liquid flow control paths to deliver the liquid hydrazine to selected locations within the bed of catalyst material and separating the entering liquid into several paths by passage of the liquid through a distribution screen.
Generally the decomposition of the liquid hydrazine into high temperature ammonia, hydrogen and nitrogen gases has previously been accomplished by causing the hydrazine to flow in contact with a catalyst material such as that produced by the Shell Oil Company under the name "Shell 405 Catalyst" which initiates and sustains the decomposition process. An example of such a hydrazine gas generator is found in U.S. Pat. No. 3,871,828.
It has been contemplated that a liquid-model propellant hydrazine-fuel pressure source might be desirable for the transpiration cooled nose tip pressurization system of, for example, ballistic reentry systems. The potential advantage of such a system resides in its ease of controllability to accommodate cooling modes as compared to solid propellants. The major concern of such a hydrazine system is in the feasibility of hydrazine gas generators of the past being capable of successful operation in the required 8000 psig level. Unfortunately, the systems now in use and as set forth in U.S. Pat. No. 3,871,828 operate solely under the influence of catalytic pellets and at normal (100-1000 psig) pressure levels. It is therefore necessary to construct a hydrazine gas generator which meets the high pressure criteria set forth hereinabove and would therefore be capable of producing the required output.